While herbivores can control the effects of added nutrients in small-scale experiments, they can be overwhelmed by pollution at larger, more realistic scales, according to Mike Gil, a marine biologist who conducted the study as a doctoral student at UF.

Gil has seen the destruction firsthand in Akumal, Mexico, where he leads a field course in marine ecology. In an attempt to answer whether herbivores were up to the task of defending reefs on their own, Gil and his team turned to mathematical modeling and found that as the area affected by nutrient pollution increases, herbivores' ability to control the resulting algae decreases, even as their populations remain the same.

Gil and his team hope their research will "guide policy-makers in creating sustainable plans for industries such as tourism and fishing, which rely on healthy reefs," according to the release.

In October, the National Oceanic and Atmospheric Administration confirmed that a global coral bleaching event had occurred -- a phenomenon in which stressed corals expel algae and turn white. If not given time to recover, bleached corals can perish. The incident announced in October was only the third time in history scientists have observed the phenomenon on a global scale, with the first occurring in 1998 and the second in 2010.